1. Field of the Invention
The present invention relates to an image forming apparatus, such as a printer, a multi-function peripheral device, and a facsimile. More particularly, the present relates to an improved paper pick-up unit and an image forming apparatus having the same.
2. Description of the Related Art
As is well known, a paper pick-up unit of an image forming apparatus picks up the uppermost sheet of paper from a plurality of papers stacked in a feeding cassette to feed it on a paper transmission path. FIG. 1 is a view of an example of a typical paper pick-up unit.
In FIG. 1, the reference numerals 100 and 110 denote a feeding cassette and a paper pick-up unit, respectively. Referring to FIG. 1, the paper pick-up unit 110 includes a pick-up rubber 111 contacting a paper P, and a pick-up housing 113 supporting the pick-up rubber 111. A pick-up shaft 115 penetrates through the pick-up housing 113 and is rotated by a driving device (not shown). A pick-up idler 117 engages the pick-up shaft 115 and is located at both ends of the pick-up housing 113.
In the above paper pick-up unit, an arc portion 111a of the pick-up rubber 111 frictionally contacts the paper P to pick up the paper P. Because the diameter of the pick-up idler 117 is smaller than the diameter of the arc portion 111a of the pick-up rubber 111, only the arc portion 111a of the pick-up rubber 111 contacts the paper P during rotation of the pick-up rubber 111. The pick-up idler 117 operates to regularly keep contact between the paper P and the pick-up rubber 111.
As described above, because only the arc portion 111a of the pick-up rubber 111 frictionally contacts the paper P, the arc portion 111a is abraded by the paper P or damaged by paper powders. As such, the coefficient of friction decreases with the passage of time, and the pick-up rubber may not function properly.
The pick-up rubber 111 has a predetermined life span, and can be averagely used for approximately fifty thousand to sixty thousand sheets of paper P. The image forming apparatus can be averagely used for more than approximately one hundred thousand sheets of paper P. In other words, the average life span of the image forming apparatus is relatively longer than that of the pick-up rubber 111. As such, if the arc portion 111a of the pick-up rubber 111 is abraded and the life span is terminated, the pick-up rubber 111 or the whole paper pick-up unit 110 needs to be replaced. To replace the conventional paper pick-up unit, a user needs the help of a specialist due to the complex construction of the paper pick-up unit. In other words, the conventional paper pick-up unit burdens the user in time and economy.
Accordingly, a need exists for an image forming apparatus having an improved paper pick-up unit with a longer lifespan.